I'm Lucy, and I'd be happy to answer your questions today. I'm very sorry to hear that this happened.
Police have discretion in deciding which crimes to pursue, when to arrest someone, and when to choose not to do so. Because of the separation of powers doctrine, a judge has no legal authority to tell police officers that they must bring someone to justice if they have chosen not to do so. In addition, police have immunity from being sued for damages related to the performance of their duties (except for very specific situations where there is a statute that says otherwise, but not arresting someone isn't a violation of anyone's civil rights). You do have the ability to go the police station and request to file a report if the first officers did not take one. And you have the ability to speak with a superior officer and explain what happened, so someone higher up is aware of your concerns with the officers' behavior. But there is unfortunately no cause of action against the police.
You have a civil case here, but it's against the people who assaulted you. Assault is both a civil wrong and a crime. When they arrived and found you in the car, the LEGAL thing to do was to call the police so an officer could remove you from the car and they could repossess it. They weren't allowed to go in after you. If they made your condition worse, you can sue for the costs of fixing that problem. If you have any pictures of bruises or other injuries, that would help. But the standard of proof for a civil case is lower, so you have the ability to file a lawsuit for damages even if police declined to proceed with a criminal case.
If you have any questions or concerns about my response, please reply WITHOUT RATING. It's important that you are 100% satisfied with my courtesy and professionalism. Otherwise, please rate my service positively so I am paid for the time I spend answering questions. If you are on a mobile device, you may need to scroll to the right. There is no charge for follow-up questions. Thank you.